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Full text of "The manufacture and properties of iron and steel"

METHODS  OF MANUFACTURE.
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fact that'-the metal contained 1.4 per cent, silicon and Oi6 per ;cent. manganese. Table XII-Gr shows the amount of oxygen needed for the charges in 'Section Xllb.
TABLE XII-G. Oxygen Needed for Pig-iron Charges.
	Cold Pig Pounds,	Direct Metal. Pounds.
Pig iron ...    ....... » ......	544 430	405,287
	7 622    '	5 674
Carbon 8.75 per cent   ......	20,415	15,198
Manganese 0.6 per cent. ..... Fe in slag.   ... ..... ........	3,267 44,270	2,432 • 34.130
Oxygen for silicon ..........	. 8.710	6.485
Oxygen for carbon ..........	27,220	20 264
Oxygen for manganese ...... Oxygen for Fe ill slag ........	950 12 650	707 9,75.1
		
Total oxygen needed ...... 'Fea03 needed ..... ........	49,530 365 100	37,207 124,020
Ore needed (94 per cent.). . . Ore used .............. .' ......	175,640 144,100	131 940    ' 116,300
		
With cold pig-iron, the ore was 82.0 per cent, of what was theoretically necessary, while with liquid metal it was 88.1 per cent. A charge of cold pig-iron should use less ore, as part of the oxidation is done by the flame. The difference will be even greater than is shown, as the series called "cold pig" was really composed of nearly 30 per cent, of molten metal. Thus in the case of the liquid metal, the amount of ore called for by theory agrees within 12 per cent. of. •the amount used. I have found: a similar agreement in the .results •of the eighty heats mentioned in the discussion .of the Bertrand Thiel process. The average heat contained 27,140 pounds of pig-iron, nearly all charged in a molten state. The average amount of ore was 7466 pounds,-or 616 pounds to the ton. The pig-iron-at Kladno was of the following-composition in per cent.-:. ' : ,.
0 3.5
P 1.5
Si 1.0        Mn 0.4
'Such an iron will demand 24 per cent, more'oxygen than an'iron containing 1.0 per cent. Si, 3.75 per'cent. C, and 0.6 per cent. Mn, and'in the Bertrand'Thiel process much oxygen is supplied by the name as it fuses the scrap in the secondary furnace, while some